The QCD axion is a hypothetical particle proposed to solve the strong CP problem. So far, there is no evidence for its existence, and the community is focusing significant efforts on exploring new ways to detect it. One of the possibilities is to find it through its conversion into photons. This idea has been used in several astrophysical contexts, for example around neutron stars, which provide an intense magnetic field that enhances this axion-photon conversion. In this talk, we will discuss a similar situation that has not yet been explored: the conversion into photons of axions living in a superradiant cloud around rotating Black Holes. We will explore this possibility taking into account the accreting plasma, which leads to a resonant axion-photon conversion. We will see that, considering realistic astrophysical environments, it is possible to detect the produced electromagnetic signal with Earth-based radio telescopes if we consider Primordial Black Holes with subsolar masses.
Organized by: Catarina Cosme